Chapter 6 Wireless Configuration

6.3 Quality of Service

This section discusses the Quality of Service (QoS) features available on the ZyXEL Device.

6.3.1 WMM QoS

WMM (Wi-Fi MultiMedia) QoS (Quality of Service) ensures quality of service in wireless networks. It controls WLAN transmission priority on packets to be transmitted over the wireless network.

WMM QoS prioritizes wireless traffic according to the delivery requirements of the individual and applications. WMM QoS is a part of the IEEE 802.11e QoS enhancement to certified WiFi wireless networks.

On APs without WMM QoS, all traffic streams are given the same access priority to the wireless network. If the introduction of another traffic stream creates a data transmission demand that exceeds the current network capacity, then the new traffic stream reduces the throughput of the other traffic streams.

The ZyXEL Device uses WMM QoS to prioritize traffic streams according to the IEEE 802.1q or DSCP information in each packet’s header. The ZyXEL Device automatically determines the priority to use for an individual traffic stream. This prevents reductions in data transmission for applications that are sensitive to latency and jitter (variations in delay).

6.3.1.1 WMM QoS Priorities

The following table describes the WMM QoS priority levels that the ZyXEL Device uses.

Table 15 WMM QoS Priorities

PRIORITY LEVEL

DESCRIPTION

voice

Typically used for traffic that is especially sensitive to jitter. Use this priority

(WMM_VOICE)

to reduce latency for improved voice quality.

 

 

video

Typically used for traffic which has some tolerance for jitter but needs to be

(WMM_VIDEO)

prioritized over other data traffic.

 

 

best effort

Typically used for traffic from applications or devices that lack QoS

(WMM_BEST_EFFORT)

capabilities. Use best effort priority for traffic that is less sensitive to latency,

 

but is affected by long delays, such as Internet surfing.

background

This is typically used for non-critical traffic such as bulk transfers and print

(WMM_BACKGROUND)

jobs that are allowed but that should not affect other applications and users.

 

Use background priority for applications that do not have strict latency and

 

throughput requirements.

 

 

6.3.2 ATC

Automatic Traffic Classifier (ATC) is a bandwidth management tool that prioritizes data packets sent across the network. ATC assigns each packet a priority and then queues the packet accordingly. Packets assigned a high priority are processed more quickly than those with low priority if there is congestion, allowing time-sensitive applications to flow more smoothly. Time-sensitive applications include both those that require a low level of latency and a low level of jitter such as Voice over IP or Internet gaming, and those for which jitter alone is a problem such as Internet radio or streaming video.

 

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ZyXEL NWA-3160 Series User’s Guide